Interpretive Summary: The Colorado potato beetle is a major pest of potatoes, tomatoes, and eggplant. In North America, this beetle is infected with a host-specific, gut-inhabiting spiroplasma (a spiral bacterium in the class Mollicutes). This spiroplasma is apparently a commensal, or harmless bacterium normally associated with the insect but may be useful in biocontrol if it can be altered to produce an insect-lethal toxin. Herein, the spiroplasma is established as a new species, Spiroplasma leptinotarsae. This information should be of use to scientists developing agents for biocontrol of the Colorado potato beetle, and to scientists investigating the systematics of bacteria.

Technical Abstract:
Spiroplasma strain LD-1T, isolated from the gut of a Colorado potato beetle, Leptinotarsa decemlineata, larva collected in Maryland, was serologically distinct from other spiroplasma species, groups, and subgroups. Similar isolates were obtained from L. decemlineata specimens collected throughout North America, Poland, and other eastern European countries, and from L. texana specimens collected in Texas. Cells of strain LD-1T were shown microscopically to be spiral with no evidence of cell wall. Originally isolated in co-culture with insect cells in DCCM medium, strain LD-1T adapted to several media in the absence of co-cultured cells. Use of anaerobic conditions allowed primary isolation in a variety of media. Primary isolates could adapt to aerobic culture in M1D. Growth occurred from 30-37 degrees C (doubling time - 7.2 h). On solid M1D medium (2.0% Nobel agar; pH 6.25; 30 degrees C), strain LD-1T produced discrete colonies with numerous satellites; colonies were more diffuse on 0.8% Nobel agar. Strain LD-1T passed filter pores of 220-nm diameter, but were retained by filters with 100-nm pores. Strain LD-1T hydrolyzed arginine, but did not utilize urea. There was evidence of week fermentation of glucose. The G+C content of the DNA was determined to be 25 +/- 1 mol%, with a genome size of 1085 kb. Extensive studies on the ecology of this spiroplasma suggest that it is host-specific to Leptinotarsa beetles. Strain LD-1T is designated the type strain (LD-1T: ATCC 43213) of a new species, Spiroplasma leptinotarsae.